Camera lens

ABSTRACT

The present disclosure provides a camera lens including six lenses, having good optical characteristics under near-infrared light and having a bright F number. The camera lens includes, from an object side: a first lens having a positive refractive power; a second lens having a negative refractive power; a third lens having a positive refractive power; a fourth lens having a positive refractive power; a fifth lens having a negative refractive power; and a sixth lens having a positive refractive power. The camera lens satisfies prescribed conditions.

TECHNICAL FIELD

The present disclosure relates to the field of camera lens, and more particularly, to a camera lens, which includes six lenses, has good optical characteristics under near-infrared light, has a bright F number (hereinafter, FNO), and is applicable to driver monitoring or the likes.

BACKGROUND

In recent years, a driver monitoring system has been developed for photographing a driver of a vehicle or the like, detecting the driver's sleepiness and side-looking based on an image and performing a warning. In such system, it is required that a camera lens for photographing the driver has good optical characteristics under near-infrared light and has a bright FNO.

In the related art, a camera lens has been proposed, which includes, from an object side: a first lens having a positive refractive power, a second lens having a negative refractive power, a third lens having a positive refractive power and a fourth lens having a positive refractive power, and the camera lens has good optical characteristics under near-infrared light. However, an FNO of the camera lens is only within a range of 1.8 to 2.6, which is not bright sufficiently.

BRIEF DESCRIPTION OF DRAWINGS

Many aspects of the exemplary embodiment can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.

FIG. 1 is a schematic diagram of a structure of a camera lens LA in accordance with Embodiment 1 of the present disclosure;

FIG. 2 is a schematic diagram of a spherical aberration, a field curvature and a distortion of the camera lens LA in accordance with Embodiment 1 of the present disclosure;

FIG. 3 is a schematic diagram of a structure of a camera lens LA in accordance with Embodiment 2 of the present disclosure;

FIG. 4 is a schematic diagram of a spherical aberration, a field curvature and a distortion of the camera lens LA in accordance with Embodiment 2 of the present disclosure;

FIG. 5 is a schematic diagram of a structure of a camera lens LA in accordance with Embodiment 3 of the present disclosure; and

FIG. 6 is a schematic diagram of a spherical aberration, a field curvature and a distortion of the camera lens LA in accordance with Embodiment 3 of the present disclosure.

DESCRIPTION OF EMBODIMENTS

A camera lens provided by exemplary embodiments of the present disclosure will hereinafter be described in detail. The camera lens LA includes, from an object side to an image side, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5 and a sixth lens L6 that constitute a lens system. A glass plate GF is arranged between the sixth lens L6 and an image plane. The glass plate GF may be a cover glass, various optical filters and the like. In the present disclosure, the glass plate GF may be arranged at different positions or may be omitted.

The first lens L1 has a positive refractive power, the second lens L2 has a negative refractive power, the third lens L3 has a positive refractive power, the fourth lens L4 has a positive refractive power, the fifth lens L5 has a negative refractive power, and the sixth lens L6 has a positive refractive power. Regarding surfaces of these six lenses, in order to correct various aberrations well, it is preferable to make each surface be an aspherical surface.

The camera lens LA satisfies conditions (1) and (2) as follows:

0.02≤|R3/R4|≤0.30   (1); and

0.60≤f3/f<1.20   (2),

where

R3 denotes a curvature radius of an object side surface of the second lens,

R4 denotes a curvature radius of an image side surface of the second lens,

f denotes a focal length of the camera lens, and

f3 denotes a focal length of the third lens.

The condition (1) defines a ratio of the curvature radius R3 of the object side surface of the second lens L2 to the curvature radius R4 of the image side surface of the second lens L2. Out of a range of the condition (1), it is difficult to achieve good optical characteristics under near-infrared light while making an FNO bright, and thus it is not preferable.

The condition (2) defines the positive refractive power of the third lens L3. Out of a range of the condition (2), it is difficult to achieve good optical characteristics under near-infrared light while making an FNO bright, and thus it is not preferable.

The camera lens LA satisfies a condition (3) as follows:

1.00≤f1/f≤2.20   (3),

where

f denotes the focal length of the camera lens; and

f1 denotes a focal length of the first lens.

The condition (3) defines the positive refractive power of the third lens L3. Within a range of the condition (3), it is advantageous to achieve good optical characteristics under near-infrared light while making an FNO bright, and thus it is preferable.

The camera lens LA satisfies a condition (4) as follows:

−1.00≤f2/f≤−0.50   (4),

where

f denotes the focal length of the camera lens; and

f2 denotes a focal length of the second lens.

The condition (4) defines the negative refractive power of the second lens L2. Within a range of the condition (4), it is advantageous to achieve good optical characteristics under near-infrared light while making an FNO bright, and thus it is preferable.

The camera lens LA satisfies a condition (5) as follows:

−2.50≤f1/f2≤−1.50   (5),

where

f1 denotes the focal length of the first lens; and

f2 denotes the focal length of the second lens.

The condition (5) defines a ratio of the focal length f1 of the first lens L1 to the focal length f2 of the second lens L2. Within a range of the condition (5), it is advantageous to achieve good optical characteristics under near-infrared light while making an FNO bright, and thus it is preferable.

The camera lens LA satisfies a condition (6) as follows:

0.15≤R5/R6≤0.35   (6),

where

R5 denotes a curvature radius of an object side surface of the third lens; and

R6 denotes a curvature radius of an image side surface of the third lens.

The condition (6) defines a ratio of the curvature radius R5 of the object side surface of the third lens L3 to the curvature radius R6 of the image side surface of the third lens L3. Within a range of the condition (6), it is advantageous to achieve good optical characteristics under near-infrared light while making an FNO bright, and thus it is preferable.

The camera lens LA satisfies a condition (7) as follows:

0.55≤R7/R8≤0.85   (7),

where

R7 denotes a curvature radius of an object side surface of the fourth lens, and

R8 denotes a curvature radius of an image side surface of the fourth lens.

The condition (7) defines a ratio of the curvature radius R7 of the object side surface of the fourth lens L4 to the curvature radius R8 of the image side surface of the fourth lens L4. Within a range of the condition (7), it is advantageous to achieve good optical characteristics under near-infrared light while making an FNO bright, and thus it is preferable.

Each of the six lenses constituting the camera lens LA satisfies the above-mentioned configuration and condition, thereby obtaining a camera lens having good optical characteristics under near-infrared light and having a bright FNO.

Hereinafter, the camera lens LA provided by the present disclosure will be described in exemplary embodiments. Reference numbers described in respective embodiments are as follows. In addition, a distance, a radius and a center thickness are all in units of mm.

f: focal length of the camera lens LA;

f1: focal length of the first lens L1;

f2: focal length of the second lens L2;

f3: focal length of the third lens L3;

f4: focal length of the fourth lens L4;

f5: focal length of the fifth lens L5;

f6: focal length of the sixth lens L6;

FNO: F number;

2ω: FOV (field of view);

S1: aperture;

R: curvature radius of an optical surface, a central curvature radius for a lens;

R1: curvature radius of an object side surface of the first lens L1;

R2: curvature radius of an image side surface of the first lens L1;

R3: curvature radius of the object side surface of the second lens L2;

R4: curvature radius of the image side surface of the second lens L2;

R5: curvature radius of the object side surface of the third lens L3;

R6: curvature radius of the image side surface of the third lens L3;

R7: curvature radius of the object side surface of the fourth lens L4;

R8: curvature radius of the image side surface of the fourth lens L4;

R9: curvature radius of an object side surface of the fifth lens L5;

R10: curvature radius of an image side surface of the fifth lens L5;

R11: curvature radius of an object side surface of the sixth lens L6;

R12: curvature radius of an image side surface of the sixth lens L6;

R13: curvature radius of an object side surface of the glass plate GF;

R14: curvature radius of an image side surface of the glass plate GF;

d: center thickness of a lens and distance between lenses;

d0: on-axis distance from the aperture S1 to the object side surface of the first lens L1;

d1: center thickness of the first lens L1;

d2: on-axis distance from the image side surface of the first lens L1 to the object side surface of the second lens L2;

d3: center thickness of the second lens L2;

d4: on-axis distance from the image side surface of the second lens L2 to the object side surface of the third lens L3;

d5: center thickness of the third lens L3;

d6: on-axis distance from the image side surface of the third lens L3 to the object side surface of the fourth lens L4;

d7: center thickness of the fourth lens L4;

d8: on-axis distance from the image side surface of the fourth lens L4 to the object side surface of the fifth lens L5;

d9: center thickness of the fifth lens L5;

d10: on-axis distance from the image side surface of the fifth lens L5 to the object side surface of the sixth lens L6;

d11: center thickness of the sixth lens L6;

d12: on-axis distance from the image side surface of the sixth lens L6 to the object side surface of the glass plate GF;

d13: center thickness of the glass plate GF;

d14: on-axis distance from the image side surface of the glass plate GF to the image plane;

nd: refractive index of d line;

nd1: refractive index of d line of the first lens L1;

nd2: refractive index of d line of the second lens L2;

nd3: refractive index of d line of the third lens L3;

nd4: refractive index of d line of the fourth lens L4;

nd5: refractive index of d line of the fifth lens L5;

nd6: refractive index of d line of the sixth lens L6;

nd7: refractive index of d line of the glass plate GF;

v: abbe number;

v1: abbe number of the first lens L1;

v2: abbe number of the second lens L2;

v3: abbe number of the third lens L3;

v4: abbe number of the fourth lens L4;

v5: abbe number of the fifth lens L5;

v6: abbe number of the sixth lens L6;

v7: abbe number of the glass plate GF;

TTL: optical length (a total optical length from the object side surface of the first lens L1 to the image plane of the camera lens along an optic axis);

LB: on-axis distance from the image side surface of the sixth lens L6 to the image plane (including a thickness of the glass plate GF).

y=(x ² /R)/[1+{1−(k+1)(x ² /R ²)}^(1/2]+) A4x ⁴ +A6x ⁶ +A8x ⁸ +A10x ¹⁰ +A ¹² +A14x ¹⁴ +A16x ¹⁶   (8)

For convenience, an aspheric surface of each lens surface uses the aspheric surfaces shown in the above formula (8). However, the present disclosure is not limited to the aspherical polynomials form shown in the formula (8).

Embodiment 1

FIG. 1 is a schematic diagram of a structure of a camera lens LA in accordance with Embodiment 1 of the present disclosure. In Embodiment 1, the camera lens LA includes a first lens L1 to a sixth lens L6. In the following, Table 1 shows respective curvature radiuses R of the object side and the image side of each of the first lens L1 to the sixth lens L6, the center thickness of each lens or the distance d between lenses, the refractive index nd and the abbe number v, Table 2 shows conic coefficients k and aspherical coefficients, and Table 3 shows 2ω, FNO, f, f1, f2, f3, f4, f5, f6, TTL and IH.

TABLE 1 Effective radius R d nd νd (mm)  S1 ∞  d0= −0.200 1.835  R1 3.84619  d1= 0.950 nd1 1.5286 ν1 76.98 1.876  R2 −18.37583  d2= 0.469 1.930  R3 −2.26393  d3= 0.425 nd2 1.6355 ν2 23.97 2.012  R4 90.55710  d4= 0.288 2.140  R5 2.41318  d5= 0.458 nd3 1.6355 ν3 23.97 2.190  R6 6.99750  d6= 0.387 2.160  R7 2.27383  d7= 0.579 nd4 1.6355 ν4 23.97 2.197  R8 3.99211  d8= 2.056 2.230  R9 −1.08854  d9= 0.585 nd5 1.6355 ν5 23.97 2.504 R10 −1.34649 d10= 0.050 2.757 R11 3.24568 d11= 0.823 nd6 1.6355 ν6 23.97 3.088 R12 3.34499 d12= 0.200 3.134 R13 ∞ d13= 0.845 nd7 1.5168 ν7 64.17 3.145 R14 ∞ d14= 0.356 3.161 Reference wavelength = 940 nm

TABLE 2 Conic coefficient Aspherical surface coefficients k A4 A6 A8 A10 A12 A14 A16  R1 −5.6103E+00  3.9583E−03  4.3282E−05 −2.2518E−03 3.1628E−04  0.0000E+00  0.0000E+00  0.0000E+00  R2  0.0000E+00 −3.5143E−03 −6.7657E−03  1.3354E−03 0.0000E+00  0.0000E+00  0.0000E+00  0.0000E+00  R3  0.0000E+00  3.0454E−02  4.4535E−03 −1.3910E−03 2.9990E−04 −1.7010E−05  0.0000E+00  0.0000E+00  R4  0.0000E+00 −8.9851E−02  4.8541E−02 −0.4828E−02 2.2455E−03 −1.4127E−04  0.0000E+00  0.0000E+00  R5  0.0000E+00 −3.6287E−02 −6.0448E−02  4.9019E−02 −2.2068E−02   5.9604E−03 −8.5908E−04  4.9787E−05  R6  0.0000E+00  6.1767E−02 −1.3024E−01  8.9876E−02 −3.6995E−02   9.3632E−03 −1.2950E−03  7.3461E−05  R7  0.0000E+00 −1.3411E−02 −2.1895E−02  5.1453E−03 1.1063E−03 −1.0754E−03  2.5041E−04 −2.0189E−05  R8  0.0000E+00 −4.5982E−03 −4.8097E−04 −1.2605E−02 8.1534E−03 −2.5686E−03  4.0922E−04 −2.5219E−05  R9 −1.4362E+00  1.5013E−02 −7.0127E−02  4.4492E−02 −1.2790E−02   2.0896E−03 −1.8783E−04  7.1095E−06 R10 −1.1402E+00 −1.5660E−03 −1.0692E−02  5.6253E−03 −3.2137E−04  −1.1324E−04  1.6494E−05 −6.4187E−07 R11  0.0000E+00 −7.9371E−02  2.5872E−02 −5.7482E−03 8.7373E−04 −9.5684E−05  6.5900E−06 −2.0304E−07 R12  0.0000E+00 −7.4496E−02  1.8651E−02 −3.5008E−03 5.3114E−04 −6.6035E−05  4.9779E−06 −1.5466E−07

TABLE 3 2ω (°) 57.87 FNO 1.57 f (mm) 5.761 f1 (mm) 6.187 f2 (mm) −3.600 f3 (mm) 5.788 f4 (mm) 7.639 f5 (mm) −67.120 f6 (mm) 42.971 TTL (mm) 8.471 LB (mm) 1.401 IH (mm) 3.092

Table 10 which will be described later shows values corresponding to the respective values of the first to third embodiments and the parameters defined by the conditions (1) to (7).

As shown in Table 10, Embodiment 1 satisfies the conditions (1) to (7).

A spherical aberration, a field curvature and a distortion of the camera lens LA in Embodiment 1 are as shown in FIG. 2. Further, the field curvature S is a field curvature in a sagittal direction and T is a field curvature in a tangential direction, and same for Embodiments 2 and 3. Regarding the camera lens LA in Embodiment 1, as shown in Table 3, FNO=1.57 is bright, and as shown in FIG. 2, it has good optical characteristics under near-infrared light.

Embodiment 2

FIG. 3 is a schematic diagram of a structure of a camera lens LA in accordance with Embodiment 2 of the present disclosure. In Embodiment 2, the camera lens LA includes a first lens L1 to a sixth lens L6. In the following, Table 4 shows respective curvature radiuses R of the object side and the image side of each of the first lens L1 to the sixth lens L6, the center thickness of each lens or the distance d between lenses, the refractive index nd and the abbe number v, Table 5 shows conic coefficients k and aspherical coefficients, and Table 6 shows 2ω, FNO, f, f1, f2, f3, f4, f5, f6, TTL, and IH.

TABLE 4 Effective radius R d nd νd (mm)  S1 ∞  d0= −0.233 1.841  R1 3.68901  d1= 0.778 nd1 1.6355 ν1 23.97 1.881  R2 6.89462  d2= 1.156 1.950  R3 −3.87222  d3= 0.300 nd2 1.6355 ν2 23.97 2.129  R4 22.77777  d4= 0.196 2.120  R5 2.33058  d5= 0.697 nd3 1.6355 ν3 23.97 2.145  R6 13.81496  d6= 0.100 2.140  R7 2.42970  d7= 0.588 nd4 1.6355 ν4 23.97 2.349  R8 2.90415  d8= 1.816 2.480  R9 −0.94228  d9= 0.431 nd5 1.6355 ν5 23.97 2.576 R10 −1.15936 d10= 0.050 2.729 R11 3.21885 d11= 0.914 nd6 1.6355 ν6 23.97 3.006 R12 4.29643 d12= 0.200 3.066 R13 ∞ d13= 0.844 nd7 1.5168 ν7 64.17 3.064 R14 ∞ d14= 0.537 3.061 Reference wavelength = 940 nm

TABLE 5 Conic coefficient Aspherical surface coefficients k A4 A6 A8 A10 A12 A14 A16  R1 −5.0794E+00   8.3586E−03 −4.4645E−03 1.5623E−04 −8.5189E−05  0.0000E+00 0.0000E+00 0.0000E+00  R2 0.0000E+00 −3.7073E−03 −5.5720E−03 2.6977E−04 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00  R3 0.0000E+00  2.1620E−02 −3.8445E−03 1.8288E−03 −2.6978E−04  9.9892E−06 0.0000E+00 0.0000E+00  R4 0.0000E+00 −7.1867E−02  2.4581E−02 −3.2199E−03  2.2626E−04 −1.8830E−05  0.0000E+00 0.0000E+00  R5 0.0000E+00 −5.0082E−02  5.3995E−03 −1.3577E−02  9.3731E−03 −3.2866E−03  5.7815E−04 −3.9838E−05   R6 0.0000E+00  4.6535E−02 −4.5342E−02 5.3034E−03 4.6777E−03 −2.2213E−03  3.9158E−04 −2.4557E−05   R7 0.0000E+00 −3.2647E−02 −7.7235E−03 2.0973E−03 4.1225E−04 1.5662E−04 −3.8511E−05  2.8653E−06  R8 0.0000E+00 −3.6998E−02  1.1350E−02 −6.0677E−03  1.3348E−03 −9.6977E−05  −8.4821E−06  1.2191E−06  R9 −1.5264E+00  −5.6963E−04 −3.4866E−02 2.4042E−02 −6.0670E−03  7.5302E−04 −4.6323E−05  1.1321E−06 R10 −1.2383E+00   7.6518E−03 −8.7257E−03 3.7939E−03 2.0800E−04 −2.0500E−04  2.5198E−05 −9.7013E−07  R11 0.0000E+00 −53448E−02  1.7633E−02 −4.8860E−03  8.8077E−04 −1.0359E−04  7.1184E−06 −2.1410E−07  R12 0.0000E+00 −4.7710E−02  1.5064E−02 −3.7587E−03  5.9915E−04 −6.2073E−05  3.7845E−06 −9.9466E−08 

TABLE 6 2ω (°) 57.72 FNO 1.57 f (mm) 5.780 f1 (mm) 11.849 f2 (mm) −5.375 f3 (mm) 4.470 f4 (mm) 16.491 f5 (mm) −33.445 f6 (mm) 15.831 TTL (mm) 8.607 LB (mm) 1.581 IH (mm) 3.092

As shown in Table 10, Embodiment 2 satisfies the conditions (1) to (7).

A spherical aberration, a field curvature and a distortion of the camera lens LA in Embodiment 2 are as shown in FIG. 4. Regarding the camera lens LA in Embodiment 2, as shown in Table 6, FNO=1.57 is bright, and as shown in FIG. 4, it has good optical characteristics.

Embodiment 3

FIG. 5 is a schematic diagram of a structure of a camera lens LA in accordance with Embodiment 3 of the present disclosure. In Embodiment 3, the camera lens LA includes a first lens L1 to a sixth lens L6. In the following, Table 7 shows respective curvature radiuses R of the object side and the image side of each of the first lens L1 to the sixth lens L6, the center thickness of each lens or the distance d between lenses, the refractive index nd and the abbe number v, Table 8 shows conic coefficients k and aspherical coefficients, and Table 9 shows 2ω, FNO, f, f1, f2, f3, f4, f5, f6, TTL, and IH.

TABLE 7 Effective radius R d nd νd (mm)  S1 ∞  d0= −0.277 1.850  R1 3.4977  d1= 1.000 nd1 1.5286 ν1 76.98 1.890  R2 20.55292  d2= 0.758 1.952  R3 −2.68956  d3= 0.380 nd2 1.6355 ν2 23.97 2.041  R4 34.27708  d4= 0.241 2.101  R5 2.27436  d=5 0.729 nd3 1.6355 ν3 21.97 2.144  R6 8.58817  d6= 0.288 2.114  R7 2.35075  d7= 0.573 nd4 1.6355 ν4 23.97 2.250  R8 3.60824  d8= 1.779 2.392  R9 −1.02672  d9= 0.504 nd5 1.6355 ν5 23.97 2.516 R10 −1.29160 d10= 0.050 2.741 R11 3.29844 d11= 0.894 nd6 1.6355 ν6 23.97 3.050 R12 3.91770 d12= 0.200 3.101 R13 ∞ d13= 0.844 nd7 1.5168 ν7 64.17 3.104 R14 ∞ d14= 0.356 3.109 Reference wavelength = 940 nm

TABLE 8 Conic coefficient Asperical surface coefficients k A4 A6 A8 A10 A12 A14 A16  R1 −4.1462E+00 4.9961E−03 −1.7601E−03 −3.9532E−04 −4.0508E−05  0 0000E+00  0.0000E+00 0.0000E+00  R2  0.0000E+00 −1.3414E−02  −1.7192E−03  1.1638E−05  0.0000E+00  0.0000E+00  0.0000E+00 0.0000E+00  R3  0.0000E+00 3.2081E−03  1.8296E−02 −6.2335E−03  1.0999E−03 −8.0220E−05  0.0000E+00 0.0000E+00  R4  0.0000E+00 −9.1652E−02   4.7103E−02 −1.2265E−02  1.6328E−03 −9.4387E−05  0.0000E+00 0.0000E+00  R5  0.0000E+00 −4.6941E−02  −1.6976E−02  1.0464E−02 −3.9082E−03  7.2057E−04 −3.1891E−05 −3.5304E−06   R6  0.0000E+00 5.5798E−02 −7.8426E−02  3.3260E−02 −7.8316E−03  1.0195E−03 −4.7724E−05 −1.0131E−06   R7  0.0000E+00 −1.4885E−02  −1.6168E−02 −8.4637E−04  1.0901E−03  2.1046E−04 −1.2187E−04 1.1037E−05  R8  0.0000E+00 −1.0805E−02  −4.9212E−04 −8.3124E−03  3.6277E−03 −5.6365E−04  2.4311E−05 9.3332E−07  R9 −1.4632E+00 9.2611E−03 −5.6719E−02  3.9828E−02 −1.2108E−02  2.0213E−03 −1.8116E−04 6.7583E−06 R10 −1.2020E+00 3.9738E−03 −1.4945E−02  9.4437E−03 −1.7451E−03  1.2902E−04 −2.9360E−06 −4.1178E−08  R11  0.0000E+00 −5.9901E−02   1.6609E−02 −2.8739E−03  2.3337E−04 −7.1747E−06  9.8413E−08 −1.0976E−08  R12  0.0000E+00 −5.2516E−02   9.7676E−03 −4.6571E−04 −1.7850E−04  3.0157E−05 −1.6944E−06 3.0208E−08

TABLE 9 2ω (°) 57.50 FNO 1.57 f (mm) 5.807 f1 (mm) 7.921 f2 (mm) −4.052 f3 (mm) 4.834 f4 (mm) 9.379 f5 (mm) −29.432 f6 (mm) 21.974 TTL (mm) 8.596 LB (mm) 1.400 IH (mm) 3.092

As shown in Table 10, Embodiment 3 satisfies the conditions (1) to (7).

A spherical aberration, a field curvature, and a distortion of the camera lens LA in Embodiment 3 are as shown in FIG. 6. Regarding the camera lens LA in Embodiment 3, as shown in Table 9, FNO=1.57 is bright, and as shown in FIG. 6, it has good optical characteristics.

Table 10 shows values corresponding to parameters defined by the conditions (1) to (7) of Embodiments 1-3.

TABLE 10 Embodiment Embodiment Embodiment 1 2 3 Notes |R3/R4| 0.025 0.170 0.078 Condition (1) f3/f  1.005 0.773 0.832 Condition (2) f1/f  1.074 2.050 1.364 Condition (3) f2/f  −0.625 −0.930 −0.698 Condition (4) f1/f2 −1.719 −2.204 −1.955 Condition (5) R5/R6 0.345 0.169 0.265 Condition (5) R7/R8 0.570 0.837 0.651 Condition (7)

REFERENCE SIGNS

LA: camera lens

S1: aperture;

L1: first lens;

L2: second lens;

L3: third lens;

L4: fourth lens;

L5: fifth lens;

L6: sixth lens;

GF: glass plate;

R: curvature radius of an optical surface, a central curvature radius for a lens;

R1: curvature radius of the object side surface of the first lens L1;

R2: curvature radius of the image side surface of the first lens L1;

R3: curvature radius of the object side surface of the second lens L2;

R4: curvature radius of the image side surface of the second lens L2;

R5: curvature radius of the object side surface of the third lens L3;

R6: curvature radius of the image side surface of the third lens L3;

R7: curvature radius of the object side surface of the fourth lens L4;

R8: curvature radius of the image side surface of the fourth lens L4;

R9: curvature radius of the object side surface of the fifth lens L5;

R10: curvature radius of the image side surface of the fifth lens L5;

R11: curvature radius of the object side surface of the sixth lens L6;

R12: curvature radius of the image side surface of the sixth lens L6;

R13: curvature radius of the object side surface of the glass plate GF;

R14: curvature radius of the image side surface of the glass plate GF;

d: center thickness of a lens and distance between lenses;

d1: center thickness of the first lens L1;

d2: on-axis distance from the image side surface of the first lens L1 to the object side surface of the second lens L2;

d3: center thickness of the second lens L2;

d4: on-axis distance from the image side surface of the second lens L2 to the object side surface of the third lens L3;

d5: center thickness of the third lens L3;

d6: on-axis distance from the image side surface of the third lens L3 to the object side surface of the fourth lens L4;

d7: center thickness of the fourth lens L4;

d8: on-axis distance from the image side surface of the fourth lens L4 to the object side surface of the fifth lens L5;

d9: center thickness of the fifth lens L5;

d10: on-axis distance from the image side surface of the fifth lens L5 to the object side surface of the sixth lens L6;

d11: center thickness of the sixth lens L6;

d12: on-axis distance from the image side surface of the sixth lens L6 to the object side surface of the glass plate GF;

d13: center thickness of the glass plate GF;

d14: on-axis distance from the image side surface of the glass plate GF to the image plane;

nd: refractive index of d line;

nd1: refractive index of d line of the first lens L1;

nd2: refractive index of d line of the second lens L2;

nd3: refractive index of d line of the third lens L3;

nd4: refractive index of d line of the fourth lens L4;

nd5: refractive index of d line of the fifth lens L5;

nd6: refractive index of d line of the sixth lens L6;

nd7: refractive index of d line of the glass plate GF;

v: abbe number;

v1: abbe number of the first lens L1;

v2: abbe number of the second lens L2;

v3: abbe number of the third lens L3;

v4: abbe number of the fourth lens L4;

v5: abbe number of the fifth lens L5;

v6: abbe number of the sixth lens L6;

v7: abbe number of the glass plate GF. 

What is claimed is:
 1. A camera lens, comprising, from an object side: a first lens having a positive refractive power; a second lens having a negative refractive power; a third lens having a positive refractive power; a fourth lens having a positive refractive power; a fifth lens having a negative refractive power; and a sixth lens having a positive refractive power, wherein the camera lens satisfies following conditions: 0.02≤|R3/R4|≤0.30; 0.60≤f3/f≤1.20, where R3 denotes a curvature radius of an object side surface of the second lens; R4 denotes a curvature radius of an image side surface of the second lens; f denotes a focal length of the camera lens; and f3 denotes a focal length of the third lens.
 2. The camera lens as claimed in claim 1, further satisfying a following condition: 1.00≤f1/f≤2.20, where f1 denotes a focal length of the first lens.
 3. The camera lens as claimed in claim 1, further satisfying a following condition: −1.00<f2/f≤−0.50, where f2 denotes a focal length of the second lens.
 4. The camera lens as claimed in claim 1, further satisfying a following condition: −2.50≤f1/f2≤−1.50, where f1 denotes a focal length of the first lens, and f2 denotes a focal length of the second lens.
 5. The camera lens as claimed in claim 1, further satisfying a following condition: 0.15≤R5/R6≤0.35, where R5 denotes a curvature radius of an object side surface of the third lens; and R6 denotes a curvature radius of an image side surface of the third lens.
 6. The camera lens as claimed in claim 1, further satisfying a following condition: 0.55≤R7/R8≤0.85, where R7 denotes a curvature radius of an object side surface of the fourth lens; and R8 denotes a curvature radius of an image side surface of the fourth lens. 